CN110591446B

CN110591446B - Printing ink for printing mobile phone shell LOGO by pad printing machine and use method thereof

Info

Publication number: CN110591446B
Application number: CN201910787748.3A
Authority: CN
Inventors: 黄武林
Original assignee: Dongguan Shunchi Plastic Technology Co ltd
Current assignee: Dongguan Shunchi Plastic Technology Co ltd
Priority date: 2019-08-23
Filing date: 2019-08-23
Publication date: 2022-03-08
Anticipated expiration: 2039-08-23
Also published as: CN110591446A

Abstract

The invention relates to the field of LOGO printing of mobile phone shells, in particular to ink for a pad printing machine to print the LOGO of the mobile phone shell and a using method thereof. The key points of the technical scheme are as follows: the formula consists of the following components in percentage by weight: 60% -84% of modified acrylic resin; 5% -35% of pigment; 0.2 to 2 percent of auxiliary agent; the balance being solvent. The use method of the ink comprises the following steps: s1 removing dust from the mobile phone shell; s2 coating the plastic shell by the pad printing machine; and S3 oven drying. The printing ink for the mobile phone shell LOGO of the pad printing machine has strong adhesion with a base material, and is not easy to have defects of incomplete printing, bottom exposure and the like.

Description

Printing ink for printing mobile phone shell LOGO by pad printing machine and use method thereof

Technical Field

The invention relates to the field of LOGO printing of mobile phone shells, in particular to ink for a pad printing machine to print the LOGO of the mobile phone shell and a using method thereof.

Background

Pad printing, which is capable of printing characters, graphics and images on the surface of an object to be printed, is now becoming an important specialty printing. The technology is very simple, a steel (or copper or thermoplastic plastic) intaglio is adopted, a curved surface transfer printing head made of a silicon rubber material is utilized, ink on the intaglio is dipped on the surface of the transfer printing head, then characters, patterns and the like can be printed by pressing the surface of an object to be transferred, then the object printed with the ink is sent to be subjected to thermal curing or photocuring, and the transfer printing is completed after the ink is cured.

The mobile phone shell is mainly made of PC material, PC is linear carbonic acid polyester, and carbonic acid group and other groups are arranged alternately in the molecule, and the groups can be aromatic, aliphatic or both. When the ink in the prior art is printed on a mobile phone shell, the defects of poor cohesiveness, easy occurrence of defects, bottom exposure and the like generally exist, and in addition, the printed LOGO has poor appearance effect consistency.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide the printing ink for the mobile phone shell LOGO of the pad printing machine, which has strong adhesion with a base material and is not easy to have defects of incomplete printing, bottom exposure and the like.

The technical purpose of the invention is realized by the following technical scheme: the formula consists of the following components in percentage by weight:

60% -84% of modified acrylic resin;

5% -35% of pigment;

0.2 to 2 percent of auxiliary agent;

the balance being solvent.

The modified acrylic resin is a copolymer of acrylic acid and 1-alkene-3-butyne, and the part of the 1-alkene-3-butyne participating in polymerization reaction is vinyl.

Through adopting above-mentioned technical scheme, modified acrylic resin can be better the bonding with cell phone case than ordinary acrylic resin, and after the cohesiveness improves, can avoid defects such as incomplete, bottom exposed. The additive can improve the performance of the ink, so that the ink can meet the production requirements in all aspects. Alkynyl exists in the 1-alkene-3-butyne, the alkynyl is a functional group with strong nucleophilic attack, the functional group can carry out nucleophilic attack on carbonyl under alkaline conditions, the PC material serving as the plastic shell of the mobile phone contains a large amount of carbonyl, and part of the carbonyl can react with the alkynyl of the modified acrylic acid to form a covalent bond in the process of curing and film forming of the printing ink, so that the adhesion of the modified acrylic resin to the PC material is enhanced.

The invention is further configured to: in the modified acrylic resin, the copolymerization degree of 1-alkene-3-butyne is 5-10%.

By adopting the technical scheme, experience shows that when the copolymerization degree of the 1-alkene-3-butyne is higher than 10%, self-crosslinking reaction is easy to occur to generate more floccules, which is not beneficial to film formation of the ink, and the color of the ink is distorted after drying, so that the pad printing effect is not ideal as if some yellow pigment is additionally added on the basis of the original pigment. When the copolymerization degree is less than 5%, the adhesion of the ink to the PC material is not significantly improved, and the desired effect is not obtained.

The invention is further configured to: the modified acrylic resin is obtained by modifying water-based acrylic resin, and the solvent is water.

By adopting the technical scheme, the waterborne acrylic resin has low VOC content, is environment-friendly and has little harm to human bodies. The whole environment of the ink is alkaline by using the substance with amino, and the whole ink has the property of a protic solvent, so that under the condition of heating, the vinyl can give protons more easily to form carbanions with strong nucleophilicity, thereby being beneficial to nucleophilic attack of acetylene groups on carbonyl groups to form covalent bonds and further improving the cohesiveness of the ink to a substrate. Water is a protic solvent, and in the aqueous solvent, substances are easier to exchange protons, so that nucleophilic attack of vinyl groups is facilitated.

The invention is further configured to: the modified acrylic resin is prepared by reacting the following raw materials in percentage by weight: 10-20% of methyl methacrylate, 5-15% of butyl methacrylate, 5-10% of acrylic acid, 5-10% of 1-alkene-3-butyne, 0.5-1% of ammonium persulfate, 2-5% of amine substances and the balance of water. By adopting the technical proposal, it is known in the field that organic matters containing a plurality of unsaturated double bonds have the problem of selectivity in the polymerization reaction, in the process of preparing the modified acrylic resin, it is not feasible to simply add 1-ene-3-butyne as an active ingredient to improve the cohesive effect on a PC base material, more alkynyl groups participate in polymerization reaction, aiming at the problem, the invention selects a cation initiator ammonium persulfate, the action mechanism is mainly that the probability of combination of the cation and the carbon-carbon double bond is high, the stability of the product formed by combination is higher than that of the product formed by combination of the cation and the carbon-carbon triple bond, and therefore, in the process of chain initiation, more carbon atoms at the 2-position in the 1-ene-3-butyne are subjected to electron transfer, so that the whole modified acrylic resin is synthesized.

In the process, the position of the 1-alkene-3-butyne for addition polymerization is a carbon-carbon double bond, so that the modified acrylic resin in the final product has more ethynyl. The whole environment of the ink is alkaline by using the substance with amino, and the whole ink has the property of a protic solvent, so that under the condition of heating, the vinyl can give protons more easily to form carbanions with strong nucleophilicity, thereby being beneficial to nucleophilic attack of acetylene groups on carbonyl groups to form covalent bonds and further improving the cohesiveness of the ink and a substrate.

The invention is further configured to: the amine substance is one or more of ammonia water, triethylamine or ethylenediamine.

Through adopting above-mentioned technical scheme, make the whole environment of printing ink be alkaline with the material that takes amino to make printing ink whole have the nature that takes place proton exchange more easily, under the circumstances of being heated, the vinyl gives the proton more easily, forms the carbanion that the nucleophilicity is strong, is favorable to acetylene to forming the covalent bond to the nucleophilic attack of carbonyl, and then promotes the cohesiveness of printing ink and substrate. And the amine substance can form ammonium salt with carboxyl, so that the water solubility of the modified acrylic resin is enhanced.

The invention is further configured to: in the process of preparing the modified acrylic resin, methyl methacrylate, butyl methacrylate, acrylic acid, 1-alkene-3-butyne and amine substances are firstly put into a reaction kettle, the temperature is raised to 45 ℃, ammonium persulfate is added, water is added while stirring at a low speed after 1min, the rotating speed is increased to 300-fold 500 turns after the reaction is carried out for 5min, the temperature is reduced to 35 ℃, the reaction is continued for 15min, and the obtained product is the modified acrylic resin.

By adopting the technical scheme, the water is added while stirring at a low speed so as to avoid the phenomenon of implosion, and after the reaction is stable, the rotating speed is increased to obtain a more uniform and stable solution.

The invention is further configured to: the auxiliary agent is one or more of a flatting agent, a wetting agent, a curing agent and a defoaming agent.

By adopting the technical scheme, the flatting agent can enable the printing ink to form a flat film after being cured. The wetting agent can wet the substrate and improve the adhesion of the ink to the substrate. The curing agent can improve the curing performance of the ink. The defoaming agent reduces the generation of bubbles in the stirring process of the ink and improves the service performance of the ink. The addition of the additives in the ink can improve the overall performance of the ink, so that the ink can meet the actual use requirements.

The invention is further configured to: the auxiliary agent also comprises a composite antioxidant, N, N '-bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, 4-hydroxyoctadecanoic acid anilide, 4' -di-tert-octyldiphenylamine and sodium sulfite.

By adopting the technical scheme, the composite antioxidant can protect alkynyl from being oxidized in the using process, and can improve the reaction efficiency of alkynyl to carbonyl in the PC substrate, so that the bonding force of the whole printing ink to the PC substrate is stronger.

Another object of the present invention is to provide a method for pad printing of a LOGO on a mobile phone case.

The technical purpose of the invention is realized by the following technical scheme: a transfer printing method of a LOGO of a mobile phone shell is characterized by comprising the following steps:

s1 removing dust from the mobile phone shell;

s2 the pad printing machine coats the plastic shell with ink;

and S3 oven drying.

Through adopting above-mentioned technical scheme, remove dust and can promote cell phone case's roughness, and then make printing ink bond on the substrate better. The shift printing machine can realize the LOGO rendition of taking the arc structural plane, and LOGO presents the third dimension and is stronger than screen printing. In the oven drying process, the ethynyl can be combined with carbonyl in the base material to form a covalent bond, so that the using cohesiveness of the ink is increased.

The invention is further configured to: the pressure control range of the pad printing machine for printing the coating on the plastic shell is 0.2-0.4 Mpa.

By adopting the technical scheme, the plastic shell can be prevented from being crushed due to overlarge pressure when the ink is printed on the plastic shell.

The invention is further configured to: the drying temperature of the oven is 55-60 ℃, and the drying time is about 15-20 min.

By adopting the technical scheme, under the drying temperature and the drying time, the solvent can be fully volatilized, and the printing ink can be fully cured to form a film.

In summary, the invention has the following beneficial effects:

firstly, the adhesive has better cohesiveness to a base material made of PC material;

secondly, the LOGO has the defects of difficult occurrence of defects such as incomplete defect, bottom exposure and the like when being rubbed;

thirdly, the printed LOGO has strong stereoscopic impression compared with the silk screen printing.

Detailed Description

The present invention will be described in detail below with reference to examples and comparative examples.

Example 1

The ink in the embodiment 1 comprises the following components in percentage by weight: 60% of modified acrylic resin; 5% of pigment; 0.2 percent of auxiliary agent; the balance being water. The modified acrylic resin is prepared by reacting the following raw materials in percentage by weight: 20% of methyl methacrylate, 10% of butyl methacrylate, 10% of acrylic acid, 5% of 1-alkene-3-butyne, 0.5% of ammonium persulfate, 2% of amine substances and the balance of water. The auxiliary agent is compounded by a curing agent and a composite antioxidant in a mass ratio of 4:1, and the composite antioxidant is compounded by N, N '-bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, 4-hydroxyoctadecanoic acid anilide, 4' -di-tert-octyldiphenylamine and sodium sulfite in a mass ratio of 1:1:1: 1. The amine substance is a mixture obtained by mixing 30 mass percent of ammonia water and ethylenediamine according to the mass ratio of 1: 1.

In the process of preparing the modified acrylic resin, methyl methacrylate, butyl methacrylate, acrylic acid, 1-alkene-3-butyne and amine substances are firstly put into a reaction kettle, the temperature is raised to 45 ℃, ammonium persulfate is added, water is added while stirring at a low speed after 1min, the rotating speed is increased to 300-fold 500 turns after the reaction is carried out for 5min, the temperature is reduced to 35 ℃, the reaction is continued for 15min, and the obtained product is the modified acrylic resin. And adding pigment, auxiliary agent and water into the prepared modified acrylic resin in sequence, and uniformly mixing under the action of a stirrer to obtain liquid, namely the ink.

The using method of the embodiment comprises the following steps: firstly, removing dust from the shell of the mobile phone; then coating the plastic shell by a pad printing machine; and finally, drying by using an oven. Wherein the pressure of the pad printing machine for printing the coating on the plastic shell is 0.2Mpa, the drying temperature of the oven is 55 ℃, and the drying time of the oven is 20 min.

Example 2

This example differs from example 1 in that the ink formulation was varied in weight percent of the components and in the method of use the process parameters were varied.

The specific differences are as follows: 70% of modified acrylic resin; 15% of pigment; 1% of an auxiliary agent; the balance being water. The modified acrylic resin is prepared by reacting the following raw materials in percentage by weight: 10% of methyl methacrylate, 15% of butyl methacrylate, 10% of acrylic acid, 10% of 1-alkene-3-butyne, 1% of ammonium persulfate, 5% of amine substances and the balance of water. The auxiliary agent is prepared by mixing a flatting agent, a curing agent, a defoaming agent and a composite antioxidant in a mass ratio of 1:1:1: 1. The composite antioxidant consists of N, N '-bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, 4-hydroxyoctadecanoic acid anilide, 4' -di-tert-octyldiphenylamine and sodium sulfite in a mass ratio of 1:1:1: 1. The amine substance is a mixture of triethylamine and ethylenediamine according to a mass ratio of 1: 1.

The pressure of the pad printing machine for printing the coating on the plastic shell is 0.3Mpa, the drying temperature of the drying oven is 60 ℃, and the drying time of the drying oven is 17 min.

Example 3

The specific differences are as follows: 84% of modified acrylic resin; 10% of pigment; 2% of an auxiliary agent; the balance being water. The modified acrylic resin is prepared by reacting the following raw materials in percentage by weight: 15% of methyl methacrylate, 10% of butyl methacrylate, 10% of acrylic acid, 10% of 1-alkene-3-butyne, 1% of ammonium persulfate, 5% of amine substances and the balance of water. The auxiliary agent is prepared by mixing a flatting agent, a wetting agent, a curing agent, a defoaming agent and a composite antioxidant in a mass ratio of 2:2:3:1: 1. The composite antioxidant consists of N, N '-bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, 4-hydroxyoctadecanoic acid anilide, 4' -di-tert-octyldiphenylamine and sodium sulfite in a mass ratio of 1:1:1: 1. The amine substance is triethylamine.

The pressure of the pad printing machine for printing the coating on the plastic shell is 0.4Mpa, the drying temperature of the drying oven is 57 ℃, and the drying time of the drying oven is 15 min.

Example 4

The specific differences are as follows: 60% of modified acrylic resin; 35% of pigment; 0.5 percent of auxiliary agent; the balance being water. The modified acrylic resin is prepared by reacting the following raw materials in percentage by weight: 20% of methyl methacrylate, 15% of butyl methacrylate, 8% of acrylic acid, 8% of 1-alkene-3-butyne, 0.5% of ammonium persulfate, 4% of amine substances and the balance of water. The auxiliary agent is prepared by mixing a wetting agent, a curing agent, a defoaming agent and a composite antioxidant in a mass ratio of 2:4:1: 1. The composite antioxidant consists of N, N '-bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, 4-hydroxyoctadecanoic acid anilide, 4' -di-tert-octyldiphenylamine and sodium sulfite in a mass ratio of 1:1:1: 1. The amine substance is ammonia water with the concentration of 30 percent.

The pressure of the pad printing machine for printing the coating on the plastic shell is 0.2Mpa, the drying temperature of the drying oven is 58 ℃, and the drying time of the drying oven is 18 min.

Example 5

The specific differences are as follows: 70% of modified acrylic resin; 25% of pigment; 1.5 percent of auxiliary agent; the balance being water. The modified acrylic resin is prepared by reacting the following raw materials in percentage by weight: 20% of methyl methacrylate, 5% of butyl methacrylate, 10% of acrylic acid, 6% of 1-alkene-3-butyne, 1% of ammonium persulfate, 3% of amine substances and the balance of water. The auxiliary agent is prepared by mixing a wetting agent, a curing agent and a composite antioxidant in a mass ratio of 1:2: 1. The composite antioxidant consists of N, N '-bis- (3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionyl) hexanediamine, 4-hydroxyoctadecanoic acid anilide, 4' -di-tert-octyldiphenylamine and sodium sulfite in a mass ratio of 1:1:1: 1. The amine substance is ethylenediamine.

The pressure of the pad printing machine for printing the coating on the plastic shell is 0.2Mpa, the drying temperature of the oven is 56 ℃, and the drying time of the oven is 19 min.

Comparative example 1

The ink of comparative example 1 was prepared from 65% by weight of an aqueous acrylic ink resin, 25% by weight of a pigment; 1% of an auxiliary agent; the balance being water. The auxiliary agent is obtained by mixing a wetting agent, a curing agent and a flatting agent according to the mass ratio of 1:1: 1. The water-based acrylic ink resin is prepared from 30% of methyl methacrylate, 25% of butyl methacrylate, 10% of acrylic acid, 1% of ammonium persulfate, 3% of amine substances and the balance of water. The amine substance is ethylenediamine. The specific preparation method is the conventional preparation method for the technicians in the field.

The pressure of the pad printing machine for printing the coating on the plastic shell is 0.2Mpa, the drying temperature of the drying oven is 57 ℃, and the drying time of the drying oven is 20 min.

Comparative example 2

The present comparative example differs from comparative example 1 in that: the weight percentages of the components of the ink formula are changed, and the process parameters in the use method are changed.

The specific differences are as follows: 80% of water-based acrylic ink resin; 15% of pigment; 1% of an auxiliary agent; the balance being water. The auxiliary agent is prepared by mixing a wetting agent, a curing agent and a flatting agent according to the mass ratio of 2:2: 1.

The pressure of the pad printing machine for printing the coating on the plastic shell is 0.4Mpa, the drying temperature of the drying oven is 59 ℃, and the drying time of the drying oven is 16 min.

Comparative example 3

The specific differences are as follows: 80% of water-based acrylic ink resin; 15% of pigment; 1% of an auxiliary agent; the balance being water. The auxiliary agent is prepared by mixing a wetting agent, a curing agent, a flatting agent and a defoaming agent according to the mass ratio of 1:2:1: 1.

The pressure of the pad printing machine for printing the coating on the plastic shell is 0.3Mpa, the drying temperature of the oven is 55 ℃, and the drying time of the oven is 18 min.

Comparative example 4

This comparative example differs from example 1 in that a different initiator was used, and it uses dibenzoyl peroxide as the initiator.

Comparative example 5

This comparative example differs from example 3 in that a different initiator was used, and in that this comparative example uses azobisisobutyronitrile as the initiator.

The samples printed in examples 1-10 and comparative examples 1-3 were taken for inspection and tested on the production line, and the results of the performance tests are shown in the following table 1:

TABLE 1

The specific description is as follows: the test criteria for the above tests were:

1. tested with a 60 ° gloss meter.

2. Referring to BS 3900: e6 test standard.

3. The test was carried out using GCMS (gas chromatography mass spectrometer) according to ZEK.01.2.08.

4. Reference is made to the GB24613 test standard.

5. Rubbing LOGO with 200-mesh sand paper repeatedly for ten times, visually inspecting and observing LOGO defects and poor bottom exposure, and counting the defective rate.

The data in the table 1 show that the ink for the pad printing machine to print the LOGO of the mobile phone shell has good pad printing performance, meets the environmental protection standard, is an environment-friendly ink, meets the current environmental protection requirement, and is suitable for popularization and application.

Meanwhile, compared with the comparative examples 1 to 3, the printing ink prepared by the printing ink resin in the invention has better adhesion to PC materials and greatly reduces the probability of defects such as incomplete printing, bottom exposure and the like compared with the printing ink prepared by some printing ink resins in the prior art, and is the printing ink specially suitable for the mobile phone shell transfer printing LOGO.

Examples 1-5 compared to comparative examples 4-5, i.e., the present invention overcomes the reduction in color that would normally occur with the addition of 1-en-3-butyne, without a significant improvement in adhesion, over some conventional methods of adding initiators.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.

Claims

1. The printing ink for printing the LOGO of the mobile phone shell of the pad printing machine is characterized by comprising the following components in percentage by weight:

60% -84% of modified acrylic resin;

5% -35% of pigment;

0.2 to 2 percent of auxiliary agent;

the balance being solvent;

the modified acrylic resin is a copolymer of acrylic monomers and 1-alkene-3-butyne, and the part of the 1-alkene-3-butyne participating in polymerization reaction is vinyl; in the modified acrylic resin, the copolymerization degree of 1-alkene-3-butyne is 5-10%; the modified acrylic resin is prepared by reacting the following raw materials in percentage by weight: 10-20% of methyl methacrylate, 5-15% of butyl methacrylate, 5-10% of acrylic acid, 5-10% of 1-alkene-3-butyne, 0.5-1% of ammonium persulfate, 2-5% of amine substances and the balance of water.

2. The ink for pad printing of a cell phone case LOGO according to claim 1, wherein: the auxiliary agent is one or more of a flatting agent, a wetting agent, a curing agent and a defoaming agent.

3. The ink for pad printing of a cell phone case LOGO according to claim 2, wherein: the auxiliary agent also comprises a composite antioxidant.

4. A transfer printing method of a LOGO of a mobile phone shell is characterized by comprising the following steps:

s1 removing dust from the mobile phone shell;

s2 pad printing machine, which coats plastic shell with the ink of any one of claims 1-3;

and S3 oven drying.